Diagnosis
PHP is diagnosed with an elevated calcium and elevated or normal intact PTH level.
When evaluating calcium, it may be prudent to draw an ionized calcium.
During pregnancy there is an increase in extracellular volume and a decrease in albumin, which may result in a factitiously low calcium, whereas the ionized calcium is normal.
Intact PTH represents the N-terminal fragment of PTH.
This is the recommended level to draw given the C-terminal or standard PTH level can be falsely elevated in patients with renal impairment due to the extended half-life and may be mildly elevated in the elderly.